Denso Ready for Piezo

Denso Corp. says it will produce diesel common-rail systems using piezo electric injectors in 2005.

The next-generation fuel injection system is under development and a specific customer cannot yet be named, says Douglas Patton, senior vice president-engineering group of Denso International America Inc.

Denso's competitor, Siemens VDO Automotive, pioneered the high-pressure, lightning-fast piezo electronic injectors. Robert Bosch Corp. and Delphi Corp. also plan to use piezo injectors as part of future common-rail systems.

Denso says its piezo actuators develop injection pressures of 29,000 psi (2,000 bar). The higher the pressure, the lower the particulate matter and oxides of nitrogen emissions. Current common-rail systems achieve about 23,000 psi (1,600 bar).

On a 2L 4-cyl. turbodiesel test engine, the 1,800-bar (26,000 psi) system boosted engine torque by 35% and engine power by 24%, while decreasing idle noise by 6.5 dB.

The 1,800-bar system employs five injection events per cycle. Diesels of the 1980s had a single injection event per cycle, which caused the trademark clatter and smoky exhaust that contributed to the demise of diesels in the U.S.